Putting the numbers in perspective with 'instream flow'

10/9/04

by Steve Marble

Clallam County, WA - During September, low flows in the Dungeness River, cited as the limiting factor for endangered salmon, drop to as little as 100 cubic feet per second.

The insteam flow number as determined by WA State Dept. of Ecology (DOE) - the theoretical amount of water to maximize salmon habitat - is deemed the most senior water right of the river due to the Endangered Species Act.

In other words, this instream flow number must be met before any other junior rights are distributed.

Toward this end, a big push is being made to conserve water. This water conservation push is why the Clallam Conservation District (CCD) is funded to pipe the leaky irrigation ditches.

One of the CCD's minor projects is saving .5 cfs, or 1/2 of a percent of the flow during minimum flow periods.

The total of the Conservation District piping efforts is expected to save 10s of cfs.

That's because agriculture is by far the major water use in the Dungeness Valley and a small savings in the total amounts to a lot of cfs.

On the other hand, exempt well use is a small percentage (less than 1%) of the total water used in the Valley.

According to Tetra-tech's model which no one I know has ever seen, the Valley will run out of water if every legally created parcel is built out and uses 5000 gallons a day. This model predicts that if we implement the WRIA 18 plan - which will limit all those wells to 500 gallons a day - then 3.5 cfs will be saved, or 3.5% of the total volume in the River at its lowest flow realized before the piping of the ditches.

(Steve Marble is an elected director of the Clallam Conservation District.)